<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .parent{
            width: 300px;
            height: 300px;
            background-color: rgb(65, 69, 71);
            /* 水平居中 */
            margin: 0 auto;
           
            display: flex;
            align-items: flex-end;
           

        }
        .parent>div{
            width: 60px;
            height: 60px;
        }
        
        .parent>div:nth-child(2){
            /* 设置自身在交叉轴的对齐方式
                flex-start/flex-end
                baseline strech */
            align-self: center;
       }
       
       
    </style>
</head>
<body>
    <div class="parent">
        <div class="div1" style="background-color: brown;">弹性元素1</div>
        <div class="div2" style="background-color: aquamarine;">弹性元素2</div>
        <div class="div3" style="background-color: blue;">弹性元素3</div>
        
        
    </div>
</body>
</html>